The application of fire retardant materials to, and processes for treating, natural and man-made fibers are well known. Intermediate products comprising fibers thus treated are rendered suitable for automotive insulation, furniture cushioning, institutional and conventional bedding, appliance insulation, acoustical insulation and a variety of building materials.
Natural fibers that can be fire retardant treated for such uses include secondary cellulose (recycled newsprint), jute, flax, cotton, gin motes, wool, etc. Man-made synthetic fibers that can be effectively treated include polyester, polypropylene nylon and rayon.
There has been a growing need for improving the fire proofing of both natural and man-made fibers. Agencies such as the Federal Trade Commission and the Consumer Products Safety Commission have imposed numerous minimum standards on a host of consumer products. Stringent flammability regulations that effect manufacturing processes include bedding such as mattresses, the furniture business, automotive industry, children's garments, and various building materials such as insulation.
Various processes for imparting flame and fire resistant qualities have long been known and used, for example, in infant wear and other textile related industries. Also, some construction materials have long been regulated in such a manner that fire resistant technology must be employed. However, most of the work conducted on flame resistant fibers has been limited to two technologies: first, in the case of cotton, such as that used in bedding applications, finely ground boric acid powder is first applied to the unwoven fiber in a “willow” machine that distributes the powder throughout the cotton prior to it being carded or woven. This approach has been used for a number of years in the bedding industry because it is relatively inexpensive and does not require a great deal of processing equipment. This process has a significant weakness in that the fine powder does not penetrate or fuse itself to the individual fibers on a consistent basis and therefore does not thoroughly bond itself to the miniscule fibers. Hence, the utilization of powders, without being in solution, for most fire retardant requirements can no longer meet the current fire retardant standards imposed by regulatory agencies.
The second most common process for applying fire retardant chemicals to either natural fibers or man-made fibers is commonly known as the “immersion” process whereby the fibers are introduced to one or more vessels holding a formula of liquid fire retardant chemicals. While this technology, if properly employed, can provide a high level of fire retardancy, it has several shortcomings. One of the more negative aspects of this approach is the fact that much equipment and energy must be employed to remove the excess liquid (typically water) from the fibers. With the recent escalating cost of energy, whether electric or natural gas, the “immersion” process contributes to a very expensive approach to adding fire retardant chemicals to the chosen fibers. Compared to the present invention, the “immersion” technique requires much more equipment and therefore consequently leads to high maintenance costs, additional downtime, and higher capital requirements for machinery replacement costs.